The present invention relates to the field of power management, and more particularly to a system providing rack level power management for a telecommunications rack utilizing a centralized DC power source.
Systems comprising multiple modules, such as telecommunication systems, are often rack mounted, in which a plurality of independent modules are secured to a common rack, which is typically 19″ wide. Each module in the rack is typically supplied with an on board power supply drawing power from a common AC mains. The on board power supply of each unit thus functions to convert AC mains power to a local DC power at the appropriate voltage for the electronics in the module.
A module which is utilizing only a small amount of energy, such as when the module is off or in a standby mode, still consumes and wastes energy. Furthermore, a multiplicity of independent small power supplies is inefficient, with supply begins to exhibit an increased temperature. This increase in temperature leads to a shortened life for the power supply. Thus, certain modules in the rack may experience early failure due to power supply stress, while neighboring modules may be operating at low utilization rates.
Power over Ethernet (PoE) is a technology enabling the delivery of power to powered devices (PD) from a power sourcing equipment (PSE) over communication cabling. A standard for PoE has been published by the Institute of Electrical and Electronics Engineers, Inc., New York, N.Y. as IEEE Std. 802.3af-2003 the entire contents of which is incorporated herein by reference. A PSE detects a PD requesting power, and in the event the PSE elects to power the PD, optionally classifies the power requirements of the detected PD, and then powers the PD within a pre-determined time after the completion of detection. PoE is a scalable technology, in which additional PDs with associated power requirements may be added by the user after an initial installation. The additional power requirements may grow to be in excess of the originally supplied power source. PoE may be supplied either from a PSE associated with switch/hub equipment, known commercially as a PoE enabled switch, or from a midspan PSE module. Midspan PSE modules may support one or more ports, with units of 1, 8, 12, 24 and 48 ports being commercially available. PoE enabled switches and midspan PSE modules are collectively denoted herein as PoE devices.
Prior art systems require a dedicated additional power source to be added as a module, feeding the additional required power. The dedicated additional power source is typically initially underutilized, and only experiences optimum utilization as the system power needs grow. This underutilized dedicated additional power source is thus unavailable in the event that one of the other modules in the system has reached maximum utilization of its on-board power supply.
Chassis and blade telecommunication switch equipment has been designed to ensure maximum up-time. The chassis comprises a housing for receiving and interconnecting by means of a backplane: blades; switch modules; management modules; power supplies; cooling fans; and other components. Chassis are expensive, however preferably are designed to provide redundancy and extremely high levels of service. For example, a plurality of cooling fan blades may be supplied, one cooling fan blade providing redundancy for an operating cooling fan blade. Similarly, chassis typically supply some level of redundancy for power sources and management modules. Unfortunately, chassis are expensive, and limit the purchaser to the use of equipment compatible with the backplane of the chassis. As described above, rack level equipment allows for the use of modules which are rack mounted and may be interconnected with standardized cabling. Thus, the use of rack level equipment provides certain flexibility and the ability to avoid an initial high cost associated with the chassis. Unfortunately, the use of rack level equipment does not provide the levels of redundancy associated with chassis equipment.
U.S. Pat. No. 5,652,893 issued to Ben-Meir et al discloses a power management system for a local area network hub. A power source, also known as a power supply, is provided having one or more elements providing a maximum power available for the system. Manageable modules are connected to the switching hub, each of the manageable modules having a memory providing information as to the power requirements of the module. A controller module comprising a microprocessor calculates the power requirements of the system and enables or disables manageable modules in accordance with power availability. Unfortunately, the system only allows for two states for each module, enabled and disabled. Thus, a module may not be powered at a low or medium power state. The embodiment of Ben-Meir is an example of chassis equipment.
What is needed therefore, and is not provided by the prior art, is a system providing rack level power management, in which power is allocated to rack mounted modules, with modules receiving a variable allocation of power responsive to power availability and the needs and priority levels associated with modules in the rack.